NONMEM Users Network Archive

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Re: OMEGA off-diagonal elements parameterized as correlations

From: saik.urien.svp <saik.urien>
Date: Wed, 08 Jul 2009 16:36:49 +0200

Paolo

You may use tools that drive the Nonmem program and output parameters in a
more friendly manner
For example Wings for Nonmem (the nmgo command expresses non diag terms as
correlations) or PsN for example

Sak

----- Original Message -----
From: Paolo Denti <paolo.denti
To: <nmusers
Sent: Wednesday, July 08, 2009 2:36 PM
Subject: [NMusers] OMEGA off-diagonal elements parameterized as correlations


> Dear all,
> I was wondering if it is possible to insert the off-diagonal elements of
> OMEGA as correlations rather than covariances, because I find it more
> intuitive.
>
> To my greatest happiness, I found the following information in a NONMEM
> chm help file:
>
> ___________________________________________________________________
> | |
> | $OMEGA |
> |_________________________________________________________________|
>
> MEANING: Supplies initial estimates for the NONMEM OMEGA Matrix
> CONTEXT: NM-TRAN Control Record
>
> USAGE:
> $OMEGA [DIAGONAL(n)|BLOCK(n)|BLOCK(n) SAME|BLOCK SAME] 5
> [[value1] [value2] [value3] ... [FIXED]] 5
> $OMEGA [DIAGONAL(n)|BLOCK(n)|BLOCK(n,m) L
> [[value1] [value2] [value3]] ... L
> [VARIANCE|STANDARD] [COVARIANCE|CORRELATON] L
> [FIXED] [ALLOFFFIX] [FIRSTFIXED] [PRINCIPAL]] L
> |BLOCK(n) SAME|BLOCK SAME] L
>
> SAMPLE:
> $OMEGA BLOCK(3) 6. .005 .3 .0002 .006 .4
>
> Reading on in the file, the [COVARIANCE|CORRELATON] sounded (in spite of
> the incorrect spelling) like the panacea I was looking for.
> Unfortunately, when I try to compile, I get a message saying that this
> option is not available in NONMEM VI. :-(
> Is this sadly only a feature planned for future versions of NONMEM?
> And if so, does anyone you know of other simple workarounds to use
> correlations instead of covariances?
>
> Thank you in advance,
> Paolo
>
>
> --
> ------------------------------------------------
> Paolo Denti, Post-Doctoral Fellow
> Division of Clinical Pharmacology
> Department of Medicine
> University of Cape Town
>
> K45 Old Main Building
> Groote Schuur Hospital
> Observatory, Cape Town
> 7925 South Africa
> phone: +27 21 404 7719
> fax: +27 21 448 1989
> email: paolo.denti
> ------------------------------------------------
>
>

Received on Wed Jul 08 2009 - 10:36:49 EDT

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